Not sure where I got the 7x from, read about it some where. Remembered it as practical, like you said higher ratio are not efficient?-)

I researched it and see 20x and higher is possible! Very cool. Thanks.

1 foot higher on the output, why do anything less?
http://www.clemson.edu/irrig/equip/ram.htm
Paragraph labeled: Valve Operation Descriptions

The swing check valve (part 4 - also known as the impetus valve) can be adjusted to vary the length of stroke (please note that maximum flow and pressure head will be achieved with this valve positioned vertically, with the opening facing up). Turn the valve on the threads until the pin in the clapper hinge of the valve is in line with the pipe (instead of perpendicular to it). Then move the tee the valve is attached to slightly away from vertical, making sure the clapper hinge in the swing check is toward the top of the valve as you do this. The larger the angle from vertical, the shorter the stroke period (and the less potential pressure, since the water will not reach as high a velocity before shutting the valve). For maximum flow and pressure valve #4 should be in a vertical position (the outlet pointed straight up).

Therefore just over 1x is possible too!
Does this agree with you?